Microscopes

Microscopes

Invented by Robert Hooke and Antoni van Leeuwenhoek

One of the most widely used tools in Biology An instrument that produces an enlarged

image of an object

Magnification & Resolution

Magnification- increase in an object’s apparent size

Resolution- the power of a microscope to clearly show detail

Types of Microscopes

Compound Light Microscope (LM) Electron Microscopes

Transmission Electron Microscope Scanning Electron Microscope (SEM)

Compound Light Microscope

LM Thin sliced (enough to be transparent) &

sometimes stained specimen is mounted on a glass slide to be viewed

The slide is placed on the stage and a light source (a light bulb in the base) directs the light upward

Compound Light Microscope

Light passes through the specimen and through the objectives lens, which is positioned directly above the specimen

Objective Lenses

A set of objective lenses is located on the rotating nosepiece enlarges the image of the specimen with different powers of magnification.

The most powerful objective lens produces an image 40 times (40X) the actual size of the specimen

Compound Light Microscope

From the objective lens, the magnified image is projected up through the body tube to the ocular lens in the eyepiece where it is magnified further (10X)

Total Magnification

Multiply the power of magnification of the lens being used (40X, 100X) by the power of magnification of the ocular or eyepiece lends (10X)

Example: 40 x 10 = 400x total power of magnification

Resolution Power

The resolution power of LM’s is limited by the physical characteristics of light

At powers of magnification beyond 2000x, the image of the specimen becomes blurry

Parts of a Compound Light Microscope

Ocular Lens Body Tube Revolving Nosepiece Objectives Stage Clips Diaphragm

Light Source Arm Stage Coarse Adjustment

Knob Fine Adjustment Knob Base

Compound Microscope

Lab